1. Field of the Invention
This invention concerns a monitoring device for semiconductor rectifiers which are arranged in a three-phase current bridge circuit.
2. Discussion of the Prior Art
A method is known by which, with several diodes parallel connected over fuses and installed on the rotor of an electrical machine, safety indicators are observed by means of a stroboscope when the machine is in operation.
A device developed by the Applicant leads each diode circuit over a special groove of the rotor. In this case, several diodes are parallel connected over fuses. Special interrogation coils are provided on the side of the stator, in which in the case of passing, if the diodes are intact, tensions are induced, which are evaluated in a corresponding device. In the case of short circuit of a diode (defective fuse) or in the case of an interruption, no tension is produced in the corresponding interrogation coil, which makes possible a clear break-down indication (Brochure "Monitoring of Rotating Rectifiers" Type "Urga", BBC 1970, DC 95055, pr-D).
However, these known methods have disadvantages. The observation of the safety indicators on rotating machines by means of the stoboscope is time consuming and only permits a periodic check. It is true that the process has been used for several years for large machines satisfies most requirements, but it is expensive, and results in added expense on the part of the machine.